Rotary wing aircraft



May 25, 1943. c. G. PULLIN 2,319,731

ROTARY WING AIRCRAFT Filed May 25, 1940 2 Sheets-Sheet 1 May 25, 1943. c. G. PULLIN 3 ROTARY WING AIRCRAFT Filed May 25 1940 2 Sheets-Sheet 2 W A WEIMEZM Patented May 25, 1943 ROTARY WING AIRCRAFT Cyril George Pullin, Genista, Newton Mearns.

Delaware Scotland, a'ssignor to Autogiro Company of America, Willow Grove,v Pa., a corporation of Application May 25, 1940, Serial No. 33 7,l72 In Great Britain March 18, 1939 11 Claims.

The present invention relates to rotative wing aircraft ofthe type having a sustaining rotor or rotors normally driven from a power unitv or power units.

According to the present invention the power transmission system between a power unit and a rotor includes a variable speed gear, for instance suitable type, for instance it may have two, three -or more speeds or. may be of the infinitely variable type, but preferably it is of the two-speed typesuch as is .used for the "over-drive"; of automobiles; Such over-drive gears usually comprise an epicyclic system, the gearfratioof which is I controlled byclutches.

a two-speed or three-speed gear, which may be Y operated manually or automatically as desired. Advantageously the selection ofthe gear is controlled by a centrifugal governor responsive to the speed of rotation of a rotor or of the power unit. The operative connection between the centrifugal governor and the variable speed gear may include a pressure fluid system.

The application of the invention to anv aircraft will be better understood from the following description with reference to the accompanythree alternative arrangements. v

In the drawings: Fig. 1 is a diagrammatic elevational ing the invention applied to an aircraft having a single sustaining rotor; Fig. 2 is a plan view corresponding to Fig. 1; Fig. 3 is a plan view of an alternative arrangeing drawings, which show by way of example ment in an aircraft having a pair of. sustaining rotors; I

Fig. 4 shows a modification? and Fig. 5 is a sectional view showing the construction of the constant speed unit referred to in Figs. 3 and 4.

Referring to Figs. 1 and 2. An aircraft has a single sustaining rotor with a hub H) and blades H which is driven through a freewheel clutch 3- l2 from a shaft I.3 extending upwardlyfrom a view show- In the arrangement shown in Fig. 3, the aircraft hasa'pair of sustaining rotors disposed on either side' of the longitudinal axis of the aircraftand driven through shafts and 3| from a gearbox 32 which is coupled to the power unit l5 by a transmission similar to that described with reference to Fig. 1 and inwhich like apparatus have the same reference numbers as in Figs. 1 and 2.

The shaft 30 carries a pinion 33 meshing with a second pinion 34 which drives a constant speed inder 36.

unit connected by a pipe 39 to the relay cylis suppliedto the constant speed unit 35 through a pipe 4| from a fluid pressure pump 'm0unted gearbox l4 which in turn is driven by a transmission shaft l5. Interposed between the shaft I5 and a power unit [8 is a fluid couplingll, for instance of the Fottinger type, and a variable speed. gear l8 which is connected to the fluid coupling by a shaft I 9.

cooling air for the power unit.

The shaft l5 carries a bevel pinion 2i meshing with a similar pinion 22 by which a centrifugal governor 23 is driven through a shaft 24. The centrifugal governor controls through a link 25 the gear selector arm 26 of the variable speed gear l8.

The centrifugal governor lect the gear ratio of the variable speed gear to maintain the speed of the shaft I5 and hence the speed of the rotor approximately constant. The variable speed gear box l 8 may be of any Also mounted on theshaft I9 is a cooling air fan 20, which provides 23 is arranged to 5e on the power unit while fluid can return .to the sump of the pump 40 through a pipe 42. The constant speed unit 35 is connected to the relay cylinder 36 by a pipe 39. The construction of the constant speed unit 35 is illustrated in Fig. 5. v .The constant speed unit 35 driven fIOIllfthe rotor shaft 30 operates to select a gear ratio of the variable gear l8 which maintains the rotor speed approximately constant by either allowing pressure fluid from the pump 40 to be delivered through the pipes 41' and 39 to .the relay cylin der or to be released from the relay cylinder through the pipe 39 to the pipe 42 and so returned to the sump of the pump.

Fig. 4 shows-a modification in which two sustaining rotors are driven from a balance gear through shafts 5i and 52 respectively coupled to shafts 53 and 54 by variable speedgears 55.

The purpose of the balance gear 50 is; to maintain substantial equality of thetorque applie-d from the power unit to each of the rotorslduring normal flight, as disclosed in my .copending British application No. 6,805 of 1939, aridin the corresponding United States application Serial No. 331,318, filed April 24, 1940; a v I Mounted on the rotor drive shaft 53 is a pin- Theunit 35' comprises a centrifugal ion 33 meshing with a second pinion 34 driving a constant speed unit 35 which controls, as described with reference to Fig. 3 the fluid Dressure within a relay cylinder 38 having a piston 31. The piston 31 is connected by a rod 88 to a lever 81 coupled by; links 88 to the selector arms 58 of the variable speed gears 85 in the transmissions from the balance gear 88 to each of the rotors to select a gear ratio which maintains the rotor speeds approximately constant.

The constant speed unit referred to as 38 is diagrammatically illustrated in Fig. 5 which is a vertical section through the unit. It comprises a lower block 89, 18 and an upper casing part H. The driving pinion 34 is mounted on a stub shaft 12 journalled in the block 88 and having at its upper end a. pinion 13 meshing with a smaller pinion 14 at the lower end of a vertical rod 15 journ-alled in the block 18. At its upper end the rod 15 carries a gear wheel 18 meshing with a wheel 11 carried on the under surfac of a plate 18 journailed at 18 in the blocli On its upper surface the plate 18 has lugs 88 on which are pivotally mounted the governor weights 8I having inward extensions 82 which engage the underside of a collar 83 at the upper end of a piston valve rod 84. Above the collar 83 is a spigot 85 to which is secured a coil spring 88 interposed between the collar 83 and a similar collar 81 carried by a member 88 having a rack 88 vertically slidable in an extension of the casing part 1I.

The vertical position of th rack member can be controlled by a toothed are 88 which engages the rack 88 and which is mounted on an arm 8| pivoted at 82 to a lug 83 on the casing part 1I. At its outer end the arm has a dependant link 84 coupled to a pilots override control for the governor.

The pistonrod 84 extends downward from the collar 83, through the centr of the plate 18 car rying the governor weights 8I, into a vertical bor in the block 10. The piston rod 84 carries two pistons mm and I88b which are slidable in an enlarged part of the vertical bore which forms a cylinder I8I. An enlarged recess I88 below the cylinder I8I is connected by a duct I82 to the pipe 42 leading to an oil sump. Near the upper end of the cylinder IN is a duct I84 leading to the pipe III extending to a pump 48 mounted on the power unit I8. The central part of the cylinder I8I between the pistons "8:1 and I88b is connected by a duct I81 to the pipe 38 connected to the relay cylinder 38. The lower end of the piston rod 84 is slidable in a bush I88 screwed into the block 18.

Th operation of the unit is as follows: The

plate 18 carrying the governor weights 8I is driven by the Wheels 11, 18, rod 15, pinions I4, 13, stub shaft 12 and pinion 34 from the pinion 33 mounted on th rotor shaft at a speed proportional to the rotor speed. Should this speed rise the governor weights 8| will tend to move outward, lifting by means of their extensions 82 the collar 83 against the action of the spring 88,

thus lifting the piston rod 84 and uncovering the duct I84. This allows oil under pressure to flow from the oil pressure pipe 4I through the duct I84 and cylinder IM to the duct I81 and pipe38 to the relay cylinder 38 causing the piston 31 to move.

When the speed of the rotor returns to normal the piston I880. cuts off the supply of oil underpressure from the duct I84. On the other hand relay cylinder and allowing the piston 81 to move back. The system is so arranged that it tends to maintain constant rotor speed by selecting a gear ratio of the variable sped gear which most nearly gives a predetermined rotor speed.

The equilibrium speed of the governor unit can b adjustedby altering the initial presure of the spring 88. When the dependant link 84 coupledto a pilot's-control for alteration of the governor equilibrium speed is moved upward the teeth 88 at the opposit end of the arm 8I engaging the rack 88 cause the rack member 88 to move downward to compress the spring 88, thereby increasing the equilibrium speed of the governor and hence the mean rotor speed.

What I claim is:

1. In an aircraft, a plurality of sustaining rotors, a power unit, gearing driven from the power unit and a power transmission to each of the rotors from said gearing, a variable speed gear and a gear selector in each of said power transmissions and coupling means to actuate the gear selectors simultaneously.

2. In an aircraft, a plurality of sustaining rotors, a power unit, gearing driven from the power unit and a power transmission to each of the rotors from said gearing, a variable speed gear and a gear selector in each of said power transmissions, coupling means to actuate the gear selectors simultaneously and means responsive to the speed of the rotor power transmissions operative to select that gear ratio of the variable speed gear which most nearly tends to maintain a-constant rotor speed.

3. In an aircraft, rotor means comprising at least one sustaining rotor, a power unit, a fluid coupling driven thereby, a variable speed gear driven from the fluid coupling and having a gear selector, a power transmission from the variable speed gear to the rotor means and a governor, driven from the transmission, operatively connected to the gear selector to select that gear ratio of the variable speed gear which more nearly tends to maintain the rotor speed at a selected value.

4. In an aircraft, rotor means comprising at leastone sustaining rotor, a power unit, a fluid coupling driven thereby, a variable speed gear driven from the fluid coupling and having a gear selector, a power transmission from the variable speed gear to the rotor means, a relay cylinder having a piston coupled to the gear selector, a governor drivenfrom the transmission, and a valve controlled by said governor regulating the fluid presure in the relay cylinder to select the gear ratio which more nearly tends to maintain the rotor speed constant at a selected value.

5. An aircraft including a pair of side-by-side oppositely rotating sustaining rotors, engine means for driving the rotors, rotor drive mechanism interconnecting the engine means and the rotors incorporating gearing for equalizing the torque between the two rotors, the rotor drive mechanism for each rotor including a variable speed transmission disposed in the drive between said gearing and the rotor, and governor means associated with one of said rotors and responsive to fluctuations in R. P. M. thereof to vary the transmission ratio in the two variable transmissions. 1

6. A construction according to claim 5, incorporating fluid coupling means in the rotor drive mechanism.

7. A construction according to claim 3, wherein two rotors are employed, together with torqueequalizing gearing between them.

8. A construction according to claim 3, with a manual control superimposed on the governor.

9. A construction according to claim 3, embodying a freewheel clutch.

CYRIL GEORGE PULLIN. 

